Issues with BT-201 Bluetooth Audio Module and Voltage Regulation

[LeonSKen]

Hello everyone,

I’ve been working on a project using the BT-201 Bluetooth audio module, and I’ve encountered several issues related to power supply and audio quality. Here’s a summary of the problems I’ve faced and the solutions I’ve tried so far:

Problems:​

1. Voltage Sensitivity: The BT-201 module is powered by a 3.7V 3200mAh Li-ion battery. Although the module is supposed to work within a 3.3V - 5V range, I’ve noticed that the audio quality deteriorates significantly when the battery voltage drops below 3.8V. The sound becomes distorted and there’s noticeable hiss and noise.
2. Inconsistent Audio Quality: Sometimes, when I set the volume to 100%, the audio quality is excellent. However, at other times, the sound quality is poor, even with the same settings. This inconsistency is puzzling, and I suspect it might be related to voltage fluctuations, but I’m not entirely sure.
3. Using a Boost Converter (XL6009): To address the voltage drop issue, I tried using an XL6009 boost converter to step up the 3.7V from the Li-ion battery to a constant 5V. While this helped stabilize the voltage, When music's volume is increasing module has shut down. It seems like the noise and ripple from the boost converter might be affecting the audio signal.

Solutions Tried:​

1. Direct 5V Power Supply: When I powered the BT-201 directly with a stable 5V source, the audio quality was much better. This confirms that the module performs well at a higher voltage.
2. Adding a Capacitor: I added a 25V 2200µF capacitor to the output of the XL6009 boost converter, which slightly improved the audio quality by reducing some of the noise. However, there’s still some distortion and poor sound quality at times.

Does anyone have experience with using BT-201 module or bluetooth amps and can suggest a more effective way to stabilize the voltage and maintain consistent audio quality?